This invention relates in general to a radial piston pump construction and more particularly to a pressure sealing valve arrangement associated therewith.
The present invention resides in an improvement to a radial piston pump having spring-loaded plungers operated by a displacing element with which a valve is associated for sealing a piston chamber from a pressure chamber, the valve being seated on a valve seat member fixed to the pump housing. Piston pumps generally have several plungers which are disposed in radial or axial relation to the pump shaft. The desired pumping action is produced by a displacing element operating on the several plungers in a predetermined phase relationship during each revolution of the pump shaft. A normally closed valve is located between each plunger and the pressure chamber located upstream thereof to seal it from the piston chambers. Each valve is opened only during certain operational phases of its plunger to conduct pressure medium to the pressure chamber. Such sealing of the plungers is relatively expensive and the pressure sealing parts are difficult to assemble. The provision of a single band-shaped valve for all plungers to simplify the sealing arrangement has been proposed. However, such sealing arrangement requires the maintenance of a precise phase relationship between the plungers to avoid increased pulsations of the pump output. Furthermore, the valve seat in such a proposed arrangement must be reground after being installed with a press fit and a divided annular spring must be fixed in a precise angular position. For that reason, it has been proposed that a separate sealing valve be provided for each plunger. While the latter proposal avoids pulsations produced by out-of-phase operation of the individual plungers, the valve arrangement is considerably more expensive since it requires more parts and more space.
It is therefore an important object of the present invention to provide a piston pump with pressure sealing valves for the individual plungers to avoid disturbance of the operational phase relationship between plungers and to simplify the valve construction and assembly.